chore(deps-dev): bump imposter.version in /examples/junit-sample

Bumps `imposter.version` from 3.38.2 to 4.2.1.

Updates `io.gatehill.imposter:distro-embedded` from 3.38.2 to 4.2.1

Updates `io.gatehill.imposter:imposter-server` from 3.38.2 to 4.2.1

Updates `io.gatehill.imposter:config-dynamic` from 3.38.2 to 4.2.1

Updates `io.gatehill.imposter:mock-openapi` from 3.38.2 to 4.2.1

---
updated-dependencies:
- dependency-name: io.gatehill.imposter:distro-embedded
  dependency-type: direct:development
  update-type: version-update:semver-major
- dependency-name: io.gatehill.imposter:imposter-server
  dependency-type: direct:development
  update-type: version-update:semver-major
- dependency-name: io.gatehill.imposter:config-dynamic
  dependency-type: direct:development
  update-type: version-update:semver-major
- dependency-name: io.gatehill.imposter:mock-openapi
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

examples/junit-sample/pom.xml

@@ -60,7 +60,7 @@
     <maven.compiler.target>1.8</maven.compiler.target>
 
     <!-- choose latest release from https://github.com/outofcoffee/imposter/releases -->
-    <imposter.version>3.38.2</imposter.version>
+    <imposter.version>4.2.1</imposter.version>
   </properties>
 
   <repositories>